Edition 8 Version of pic (July 1985).

[unix-history] / usr / src / local / ditroff / ditroff.okeeffe / pic / for.c

#ifndef lint
static char sccsid[] = "@(#)for.c       3.1 (CWI) 85/07/30";
#endif lint

#include <stdio.h>
#include "pic.h"
#include "y.tab.h"

#define SLOP    1.001

typedef struct {
       char    *var;   /* index variable */
       float   to;     /* limit */
       float   by;
       int     op;     /* operator */
       char    *str;   /* string to push back */
} For;

For     forstk[10];     /* stack of for loops */
For     *forp = forstk; /* pointer to current top */

forloop(var, from, to, op, by, str)     /* set up a for loop */
       char *var;
       float from, to, by;
       int op;
       char *str;
{
       dprintf("# for %s from %g to %g by %c %g \n",
               var, from, to, op, by);
       if (++forp >= forstk+10)
               fatal("for loop nested too deep");
       forp->var = var;
       forp->to = to;
       forp->op = op;
       forp->by = by;
       forp->str = str;
       setfval(var, from);
       nextfor();
       unput('\n');
}

nextfor()       /* do one iteration of a for loop */
{
       /* BUG:  this should depend on op and direction */
       if (getfval(forp->var) > SLOP * forp->to) {     /* loop is done */
               free(forp->str);
               if (--forp < forstk)
                       fatal("forstk popped too far");
       } else {                /* another iteration */
               pushsrc(String, "\nEndfor\n");
               pushsrc(String, forp->str);
       }
}

endfor()        /* end one iteration of for loop */
{
       struct symtab *p = lookup(forp->var);

       switch (forp->op) {
       case '+':
       case ' ':
               p->s_val.f += forp->by;
               break;
       case '-':
               p->s_val.f -= forp->by;
               break;
       case '*':
               p->s_val.f *= forp->by;
               break;
       case '/':
               p->s_val.f /= forp->by;
               break;
       }
       nextfor();
}

char *ifstat(expr, thenpart, elsepart)
       double expr;
       char *thenpart, *elsepart;
{
       dprintf("if %g then <%s> else <%s>\n", expr, thenpart, elsepart? elsepart : "");
       if (expr) {
               unput('\n');
               pushsrc(Free, thenpart);
               pushsrc(String, thenpart);
               unput('\n');
               if (elsepart)
                       free(elsepart);
               return thenpart;        /* to be freed later */
       } else {
               free(thenpart);
               if (elsepart) {
                       unput('\n');
                       pushsrc(Free, elsepart);
                       pushsrc(String, elsepart);
                       unput('\n');
               }
               return elsepart;
       }
}